20 Gauge vs 12 Gauge

First let me say I know NOTHING about guns. Im hoping to get opinions on choosing a defender rifle. I was originally interested in buying a 12 gauge. When I went to a gun shop to ask questions and get info, I was told that a 20 gauge would be better suited for what I needed it for (home protection). I was told it has less recoil and its easier to handle than a 12 gauge. Then, while talking to my neighbor, I was told that the 12 gauge was better and easier to handle. Saying that his frail wife could handle the 12 gauge just fine. He also went on to say that the 20 gauge was being discontinued. I did do a search on Google for any articles that confirm this and I was unable to find a thing that stated 20 gauges were being discontinued.
I'm very confused and need advice from someone that KNOWS about 12 & 20 gauge shotguns. Help!

You will get diehard 20 ga fans that will swear to their 20.
I find the recoil to be about the same.
The cost of the shells is the same price.
With 12 ga you get more shot, more powder but the same velocity for the shot and range.
There is more shot out to catch the doves or what ever.
Did you get the "cost of shells is the same".
I have seen people with the 20 ga has less recoil for women BS.
My wife will only shoot 12 ga and has had no problem with the recoil.

The 20 gauge is not being discontinued I think he is confused with the 16 gauge. As for recoil as long as you have a well designed stock and possibly a recoil pad recoil should not be that much of an issue.

Within both gauges there are different levels of power. You can get light or heavy loads for both.
Either one will do great for home defense. They are both popular and will be around for a long time.
The 12 is a little more versatile than the 20. There is a wider variety of loads out there for it. But the difference is small. When comparing apples to apples the 12 will be able to generate a bit more recoil. This is not very significant though so don't base any decision on that.
I think you may have an easier time finding suitable practice ammo with a 12 gauge although, again, the difference will be small.
20 gauage guns are generally a little bit lighter than their larger bore cousins.
If you are looking for a defensive arm, I think this is where the 12 is a better choice. There are a lot more guns made in a "combat" style in 12 gauge than in 20.
For example, the Winchester catalog has one selection, the Defender. It is only in 12
The remington catalog has three or four tactical shotguns, all available in 12 gauge only.
The Mossberg catalog shows like 17 different tactical or combat configurations and none of them are offered in a 20.
That isn't to say you can't buy a pump 20 gauge and put an 18 inch barrel on it and be fine. That would make a great home defense weapon. It doesn't have to be anything fancy or tactical looking to protect yourself with. I just think the 12 is the way to go for that.
Then there is the ammo. Standard buckshot and slugs in either gauge will work fine for you. However, there has been more load development in the 12. Things like reduced recoil tactical buckshot loads and stuff are not available in a 20.
If you want to play with some specialty loads that you can find once in a while they are almost always in 12 too.

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They're both great shotguns. The 12 kicks a little harder, but both are fine for home/self defense, close range deer hunting, and small game, but you'll be better off with the 12 if you're going for migratory birds. I have not heard anything to suggest that the twenty is phasing out, and have no reason to believe that it is phasing out. Both of them are rock solid, very practical and versatile, and should be around for a long time. That's just my opinion after 35 years of experience with both of them for recreational shooting, hunting, home defense, and law enforcement, although the 12 is clearly the choice for law enforcement.

Recommendations For a Short Barrel 20 ga Defender

Ok,
I think I'm going to go with a 20 ga pump (short barrel) defender. Can I please have some recommendations as what to buy? Like I said, I know nothing about guns period. Im female living alone with an "alert dog" who will surely give me a heads up in case of an intruder.
You know, I never thought about owning a gun until the state of our economy took a nose dive. People are desperate now. Living alone, I sure as HELL am not going to be a sitting duck.